U.S. government medical researchers intentionally infected hundreds of people in Guatemala, including institutionalized mental patients, with gonorrhea and syphilis without their knowledge or permission more than 60 years ago.

Many of those infected were encouraged to pass the infection onto others as part of the study.

About one third of those who were infected never got adequate treatment.

On Friday, Secretary of State Hillary Clinton and Health and Human Services Secretary Kathleen Sebelius offered extensive apologies for actions taken by the U.S. Public Health Service.

"The sexually transmitted disease inoculation study conducted from 1946-1948 in Guatemala was clearly unethical," according to the joint statement from Clinton and Sebelius. "Although these events occurred more than 64 years ago, we are outraged that such reprehensible research could have occurred under the guise of public health. We deeply regret that it happened, and we apologize to all the individuals who were affected by such abhorrent research practices."

Secretary Clinton called Guatemalan president Alvara Cabellaros Thursday night to reaffirm the importance of the U.S. relationship with the Latin American country. President Barack Obama called Cabellaros Friday afternoon, according to a statement from White House press secretary Robert Gibbs.

"The people of Guatemala are our close friends and neighbors in the Americas," the government statement says. "As we move forward to better understand this appalling event, we reaffirm the importance of our relationship with Guatemala, and our respect for the Guatemalan people, as well as our commitment to the highest standards of ethics in medical research."

During a conference call Friday with National Institutes of Health Director Francis Collins and Assistant Secretary of State Arturo Valenzuela, officials noted that there were no formalized regulations regarding protection of human studies during the 1940s.

In addition to the apology, the U.S. is setting up commissions to ensure that human medical research conducted around the globe meets "rigorous ethical standards." U.S. officials are also launching investigations to uncover exactly what happened during the experiments.

The episode raises inevitable comparisons to the infamous Tuskegee experiment, the Alabama study where hundreds of African-American men were told they were being treated for syphilis, but in fact were denied treatment. That U.S. government study lasted from 1932 until press reports revealed it in 1972.

The Guatemala experiments, which were conducted between 1946 and 1948, never provided any useful information and the records were hidden.

Wellesley College

Susan Reverby, a professor of women's studies at Wellesley College in Massachusetts, discovered records documenting U.S. experiments that infected Guatemalans with gonorrhea and syphilis.

They were discovered by Susan Reverby, a professor of women's studies at Wellesley College in Massachusetts and were posted on her website.

According to Reverby’s report, the Guatemalan project was co-sponsored by the U.S. Public Health Service, the NIH, the Pan-American Health Sanitary Bureau (now the Pan American Health Organization) and the Guatemalan government. The experiments involved 696 subjects — male prisoners and female patients in the National Mental Health Hospital.

The researchers were trying to determine whether the antibiotic penicillin could prevent syphilis infection, not just cure it, Reverby writes. After the subjects were infected with the syphilis bacteria — through visits with prostitutes who had the disease and direct inoculations — it is unclear whether they were later cured or given proper medical care, Reverby notes. While most of the patients got treatment, experts estimate as many as a one-third, did not.

The STD experiments were conducted with the cooperation of the Guatemalan government. During that time, the U.S. -- which had a long association with the Guatemalan military -- exerted a powerful influence in the Latin American country, largely in order to protect the interests of the American-based United Fruit Company. In 1954 the U.S. CIA helped overthrow Guatemala’s democratically elected president because of land reforms that opposed the multinational corporation.

Video: U.S. apologizes for STD experiments in Guatemala

Transcript of: U.S. apologizes for STD experiments in Guatemala

LESTER HOLT, anchor:today from
President Obama
for something that happened more than 60 years ago.
The US
conducted secret
medical experiments
that involved the -- intentionally infecting Guatemalan mental patients with
sexually transmitted diseases
. Tonight
Guatemala
is calling it a crime against humanity and says it may take the case to an international court.
NBC
's chief science correspondent
Robert Bazell
broke the story this morning. He has this late update tonight.

ROBERT BAZELL reporting:The secret experiments took place in
Guatemala
between
1946
and
1948
, financed by the
US government
and supervised by
US government
doctors.
Susan Reverby
, a professor at
Wellesley College
, who has studied medical malfeasance extensively, found the evidence in
US government
records.

Dr. SUSAN REVERBY:I thought that -- frankly, that I wouldn't get shocked but I thought this one was pretty horrific. The details of how they did it were pretty graphic.
And I
was actually quite surprised.

BAZELL:The doctors inoculated almost 700 prostitutes, institutionalized mental patients and prisoners with the germs that cause either syphilis or gonorrhea.

BAZELL:The subjects did not give their permission and were not told what was happening. They were injected in the skin, the genitals, even the spine. Infected female prostitutes were also sent into the prison and
mental hospital
to infect men.

Dr. REVERBY:They knew that this wasn't appropriate. The surgeon general even said we couldn't do this in the
United States
.

BAZELL:The experiments were designed to study the effects of penicillin on
sexually transmitted disease
. Still, as many as a third of the patients were not properly treated. Today, outrage on the streets of
Guatemala
's capital and in newspapers online, and from Guatemalan-Americans in
Los Angeles
.

Mr. RAFAEL CASTILLO (Guatemalan Unity Information Agency):Actually, I'm very surprise, upset. It's like a combination of feelings because it's been a long time already, but it's something outrageous, I would call it.

Unidentified Man:What is now called the
Tuskegee experiment
began here in
1932
.

BAZELL:From
1932
until the research was revealed in the press in
1972
,
government
doctors lied to hundreds of
African-American
men who were infected naturally. The doctors, some also involved in the
Guatemala
experiment, told the men they were getting treatment, but in fact they were not. Despite numerous apologies, that incident has left many
black Americans
weary of the medical establishment.

Dr. BILL RELEFORD (Health Educator):It still resonates after generations and generations. And people still talk about it. So this legacy of mistrust in the
African-American
community still exists.

BAZELL:Even though the
Guatemala
experiment took place more than 60 years ago, officials today call on the prestigious
Institute of Medicine
to launch a full investigation and identify steps to prevent further abuses. Another example of the most vulnerable being victimized and of doctors who ignore their pledge to
first do no harm
.
Robert Bazell
, NBC News, New York.